Book Image

DART Cookbook

By : Ivo Balbaert
Book Image

DART Cookbook

By: Ivo Balbaert

Overview of this book

Table of Contents (18 chapters)
Dart Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Using regular expressions


Regular expressions are an indispensable tool in every programming language to search for matching patterns in strings. Dart has the RegExp class from dart:core, which uses the same syntax and semantics as JavaScript.

How to do it...

We use RegExp in the following code (see using_regexp.dart) to quickly determine whether a credit card number seems valid:

var visa = new RegExp(r"^(?:4[0-9]{12}(?:[0-9]{3})?)$");
var visa_in_text = new RegExp(r"\b4[0-9]{12}(?:[0-9]{3})?\b");
var input = "4457418557635128";
var text = "Does this text mention a VISA 4457418557635128 number?";

void main() {
  print(visa.pattern);
  // is there a visa pattern match in input?
  if (visa.hasMatch(input)) {
    print("Could be a VISA number");
  }
  // does string input contain pattern visa?
  if (input.contains(visa)) {
    print("Could be a VISA number");
  }
  // find all matches:
  var matches = visa_in_text.allMatches(text);
  for (var m in matches) {
    print(m.group(0));
  }
visa_in_text...